Brake device

ABSTRACT

The invention relates to a brake device for braking a moving brake body ( 2 ) by means of pressing a brake element ( 3, 4 ) onto the brake body ( 2 ), wherein a conversion device ( 7 ) is provided for converting a rotational movement of a brake drive shaft ( 9 ) into a translational movement of the brake element ( 4 ) in the direction of the brake body ( 2 ), wherein a rotary percussion mechanism ( 8 ) is connected between the brake drive shaft ( 9 ) and the conversion device ( 7 ).

BACKGROUND OF THE INVENTION

The invention relates to a brake device for reducing the speed of amoving body by braking.

The relevant safety regulations for wind power plants dictate that twomutually completely independent and redundant brake systems arerequired. In older wind power plants these redundant brake systems arerealized in the form of brakes which can be operated independently fromeach other, in which case an external system had usually been designedaerodynamically and a brake system had been designed mechanically. Inmodern wind power plants both brake systems may be realized asaerodynamic brakes with mechanical systems for twisting the rotor bladesabout their longitudinal axes, approximately normal to the rotor axis.In such installations with single blade adjustment or so-called pitchinstallations mechanical brakes are no longer required as an elementarycomponent of the safety concept. However, even in these modern windpower plants mechanical brakes are employed in order to allow stoppingof the rotor after aerodynamic braking.

Maintenance work in the region of the rotor or the rotor recess,respectively, is only possible once the rotor has come to a completestandstill. The mechanical rotor brakes employed for this purpose arealso referred to as service and support brakes. For this purpose, inolder plants, hydraulic brakes are normally also used for deceleratingthe rotation of the rotor. In compact structures, such hydraulic brakesallow to generate particularly high clamping and braking forces. Inaddition, hydraulic brakes attain a response performance which providesthe full braking power within a very short period of time. However, ithas been shown that when using these conventional hydraulic andelectro-mechanical brakes as service and support brakes, in addition tothe aerodynamic brake, brought about by blade adjustment, damage to thebrakes themselves and the components which have been stopped may occur.

Although electro-mechanical brake calipers serving as service andsupport brakes for wind power plants have relatively high brakingforces, which, moreover, can be increased by interconnecting atransmission system, the electro-mechanical brake caliper per se does,however, not have the compactness which can be attained by a hydraulicbrake caliper. It is understood that this consideration does not takeinto account that further system components are required for generatinghydraulic pressure. The known pneumatic brake calipers likewise do notattain the desired compactness since the forces of a pneumatic powergenerator are always less than those of a hydraulic power generator ofidentical size.

SUMMARY OF THE INVENTION

It is, therefore, the object of the invention to provide anelectro-mechanical brake caliper which is capable of generating highbraking forces and which is designed in a very compact manner.

This object is attained in accordance with the invention by a brakedevice for reducing the speed of a moving brake body by pressing a brakeelement onto the brake body, a conversion means for converting arotational movement of a brake drive shaft into a translation movementof the brake element in the direction towards the brake body beingprovided, characterized in that a rotary impact mechanism is fittedbetween the brake drive shaft and the conversion means.

Advantageous further developments of the inventive concept form thesubject of the subsidiary claims.

In the brake device according to the invention for reducing the speed ofa moving brake body, in particular a brake disk, a brake element ispressed onto the brake body. A conversion means, for example a spindledrive, serves to convert a rotational movement of a brake drive shaftinto a translational movement of the brake element to be pressed ontothe brake body. The brake device according to the invention providesthat a rotary impact mechanism is fitted between the brake drive shaftand the conversion means. A rotary impact mechanism operating accordingto the operating principle of an impact screw drive mechanism createspercussive energy in a tangential direction, so that high tractionforces can be attained which in a brake may be equated with high brakingforces.

The advantage of the brake device according to the invention is thatonly minimal space is required for the rotary impact mechanism so thatvery high clamping forces result in these electro-mechanical brakecalipers. Such brake calipers may be used both in translationally movedas well as in rotating brake bodies, i.e. in brake disks. The operatingprinciple of the brake device is not limited to one concreteapplication. However, the brake device claimed may be employedparticularly advantageously in systems where high braking forces are tobe brought about, simultaneously having the smallest possibleinstallation size, such as, for example, in service and support brakesof wind power plants. Examples of application based on similar problemdefinitions, i.e. where high braking forces are required in smallspaces, are to be found in a multitude of industrial applications, butalso in motor vehicle technology, in particular railway technology.

In a preferred embodiment, the rotary impact mechanism is composed of animpact armature and a driving wheel, the said impact armature and thedriving wheel being pressed against one another by an elastic force sothat the impact armature and the driving wheel are in engagement withone another via axially projecting drivers, and that a torque can betransmitted from the brake drive shaft to the conversion means. Byovercoming the elastic force and by separating the interlocked armaturefrom the driving wheel by shifting the brake drive shaft into the axialdirection, a transfer or transposition of the impact armature occurs, sothat an impact impulse in the tangential direction is exerted on thedriving wheel when rotation continues. In this configuration the drivingwheel is preferably arranged in an axially stationary manner while theimpact armature can be displaced in the axial direction and is impingedby the elastic force.

In practice, the rotary impact mechanism may be a V-grooved impactmechanism, wherein, for example, V-shaped grooves are formed in thedriving wheel, into which drivers of the impact armature, projecting inaxial direction and designed as cams, engage. This configuration has theadvantage that it requires a very short building length in the axialdirection of the rotary impact mechanism.

In principle, it is also conceivable for the rotary impact mechanism tobe a cam impact mechanism, wherein drivers are provided both on thedriving wheel as well as on the impact armature, projecting in the axialdirection and entering into mutual engagement for torque transmission.

It is important for the mode of operation of the rotary impact mechanismthat a transfer of the impact armature occurs when a set desired torqueis exceeded. This is realized in the brake device according to theinvention in that the impact armature, via a driving pin, is inengagement with a helical control groove of the brake drive shaft. Ifthe brake device is to be activated, i.e. if the brake element is to beshifted from a free-wheeling position into a braking position, a torqueis first applied via the brake drive shaft, which torque, via the impactarmature, the drivers and the driving wheel, is applied to theconversion means, moving the brake element into the direction towardsthe brake body. If the brake element abuts against the brake body, thedriving wheel comes to a stop. This consequently stops the impactarmature from turning further while the rotation of the brake driveshaft continues. The control groove is now configured in such a mannerthat the driving pin of the impact armature in the helical controlgroove is guided as in a shifting gate and is shifted in the axialdirection so that the impact armature is released from the driving wheelin the axial direction. As the impact armature is transferred, i.e. isno longer in engagement with the driving wheel, it is rapidlyaccelerated by the rotational movement of the brake drive shaft and issimultaneously pressed once again into the direction towards the drivingwheel by the elastic force so that the result is an immediatere-engagement between the impact armature and the driving wheel. Theabrupt impulse causes the driving wheel to continue turning slightly, sothat the braking force onto the brake body increases further. Thisprocess recurs repeatedly until it is ensured that no greater brakingforce can be applied to the brake body.

It is, therefore, not only the elastic force, pressing the impactarmature against the driving wheel, which has a significant influence onthe braking torque, but also the mass of the impact armature. It isconsidered advantageous for the brake drive shaft to be surrounded by ahelical spring exerting the elastic force on the impact armature, sincehigh elastic forces can be brought about in this manner in a very smallspace.

The driving wheel as such is advantageously coupled directly to theconversion means. The connection is, in particular, realized in anintegral manner. Particularly preferably the driving wheel forms anintegral part of a threaded spindle of the conversion means. Thisthreaded spindle engages in a threaded cup which can be shifted in theaxial direction and which is guided in a housing of the brake device.The threaded cup, in turn, is connected to the brake element and bringsabout the actual braking process by axial displacement. It is consideredadvantageous for the brake element to be adjustable from a free-wheelingposition into a brake position by at least one complete rotation,preferably a plurality of rotations of the threaded spindle. The pitchof the threaded spindle may be so selected that the conversion means isself-locking. In this case, the drive unit coupled to the brake driveshaft may be switched off without the risk of the braking force fading.

A substantially more compact design is attained with the brake deviceaccording to the invention than would have been possible with a directlycoupled spindle drive. Moreover, the self-locking feature permitslocking the brake device which is not readily realizable, i.e. notwithout additional valve means, in hydraulically and pneumaticallyoperated pistons. In this context, it is important that once the brakingtorque has been applied, this is preserved even if the energy foroperating the brake drive shaft is no longer available.

The drive energy for operating the brake drive shaft may be broughtabout electrically, pneumatically, hydraulically or via a motor.

BRIEF DESCRIPTION OF THE DRAWING

The invention is elucidated in more detail in what follows by way of aworking example shown in schematic drawings. There is shown in:

FIG. 1 a sectional view of the brake device according to the inventionand

FIG. 2 a perspective view of the rotary impact mechanism of FIG. 1.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 shows a sectional view of a brake device 1 for reducing the speedof a brake body 2, which in the present embodiment is formed by arotating brake disk. Mutually opposite brake elements 3 and 4 arepressed onto the brake disk, the right brake element 3 in the imageplane being arranged in a stationary manner. The left brake element 4 inthe image plane can be shifted in the axial direction of the brakedevice 1. The brake elements 3 and 4 are altogether retained or mountedon a brake caliper 5, overlapping the brake body 2.

The brake device 1 comprises a housing 6, connected to the brake caliper5. In the housing 6 a conversion means 7 is provided on the one hand anda rotary impact mechanism 8 on the other hand. The rotary impactmechanism 8 is driven by a brake drive shaft 9, which, in turns isdriven by a motor 10 which is connected to the housing 6. The rotationalaxis D of the brake drive shaft 9 forms the longitudinal axis of thebrake device 1.

The brake drive shaft 9 is surrounded by a helical spring 11, which, onthe one hand, takes support on the end face of the motor 10 facing thehousing 6 and, on the other hand, presses an impact armature 12 of therotary impact mechanism 8 against a driving wheel 13 of the rotaryimpact mechanism 8.

The brake drive shaft 9, the impact armature 12 and the driving wheel 13are also shown in FIG. 2. It can be seen that the impact armature 12comprises drivers 14 in the form of diametrically arranged cams,projecting in the axial direction, which engage with drivers 15 at theend face of the driving wheel 13, if the impact armature 12 is forcedagainst the driving wheel 13 by the helical spring 11.

A driving pin 16 constitutes a further important component, projectingradially inwardly from the impact armature 12 and, in the installedposition, engaging with a helical control groove 17.

In FIG. 1 the drivers 14 and 15 are in mutual engagement, the helicalspring 11 forcing the impact armature 12 into the direction towards thedriving wheel. Due to the configuration of the control groove 17, theimpact armature 12 is in its extreme position, as it were, and has beenshifted as far to the right as possible in the image plane of FIG. 1. Ifthe motor 10 puts the brake drive shaft 9 into rotation, the impactarmature 12 is initially moved synchronously with the driving wheel 13until the latter comes to a rest when the brake element 4 abuts againstthe brake body 2. At this moment the further rotation of the brake driveshaft 9 causes the drivers 14 of the impact armature to disengage inthat the driving pin 16 in the control groove 17 is shifted to the back,i.e. to the left in the image plane, against the elastic force of thehelical spring 11. This causes the disengagement between the drivers 14and 15 and the drivers 14 of the impact armature 12 to be transferred inorder to be rotated further by 180° and simultaneously to be pressedonce again into the direction towards the driving wheel 13 by theelastic force of the helical spring 11. The drivers 14 of the impactarmature impact abruptly on the corresponding drivers 15 of the drivingwheel 13, so that the latter is rotated a little further. This processis repeated several times until the driving wheel 13 comes to astandstill.

The driving wheel 13 forms an integral part of a threaded spindle 18,which in the present embodiment is configured as a hollow spindle. Thethreaded spindle 18 has an external thread and engages with a threadedcup 19, surrounding the threaded spindle 18. The threaded cup 19 isguided inside the housing 6 and is protected against axial twisting, sothat the threaded cup 19 exclusively performs an axial movement inducedby the rotation of the threaded spindle 18. This axial movement is usedto displace the brake element 4 from a free-wheeling position into thebraking position shown in FIG. 1. A braking force is applied in thiscase which is absorbed by an axial bearing 20 provided between anabutment shoulder of the housing 6 and the driving wheel 13. In thepresent embodiment, the axial bearing 20 is situated outside the innerregion claimed by the driving pins 14 and 15, surrounding the region ofthe driving pins 14 and 15 in an annular fashion, as it were.

The driving pins 14 and 15 are configured in such a manner that thebrake device 1 functions even if the rotational direction of the brakedrive shaft 9 is reversed, so that the brake element 4 can be lifted offthe brake body 2 after only a few rotations of the threaded spindle 18.

What is claimed is:
 1. A brake device for reducing the speed of a movingbrake body by pressing a brake element onto the brake body, a conversionmeans for converting a rotational movement of a brake drive shaft into atranslation movement of the brake element in the direction towards thebrake body being provided, wherein a rotary impact mechanism is fittedbetween the brake drive shaft and the conversion means, said rotaryimpact mechanism including an impact armature and an elastic memberwhich is directly supported by the impact armature and configured toapply an elastic force by which the impact armature is urged in adirection of the brake element, wherein the rotary impact mechanismcomprises a driving wheel, said impact armature and the driving wheelbeing pressed against one another by the elastic force so that theimpact armature and the driving wheel are in engagement with one anothervia axially projecting drivers while transferring a torque from thebrake drive shaft to the conversion means, in the course of which, byovercoming the elastic force and by separating the engaged impactarmature from the driving wheel by shifting the brake drive shaft intothe axial direction a transfer of the impact armature occurs, so that arotary impact impulse is exerted on the driving wheel when rotationcontinues and wherein the impact armature engages with a helical controlgroove of the brake drive shaft via a driving pin.
 2. The brake deviceof claim 1, wherein the rotary impact mechanism is a V-grooved rotarymechanism.
 3. The brake device of claim 1, wherein the rotary impactmechanism is a cam rotary mechanism.
 4. The brake device of claim 1,wherein the elastic member is a helical spring in surroundingrelationship to the brake drive shaft.
 5. The brake device of claim 1,wherein the driving wheel is connected to a threaded spindle of theconversion means.
 6. The brake device of claim 5, wherein the drivingwheel forms an integral part of a threaded spindle of the conversionmeans.
 7. The brake device of claim 6, wherein the threaded spindle isin engagement with a threaded cup guided inside a housing and axiallydisplaceable, the said threaded cup being connected to the brakeelement.
 8. The brake device of claim 5, wherein threaded spindle has aself-locking pitch.
 9. A brake device for reducing the speed of a movingbrake body, comprising: a brake element movable in a direction of thebrake body; a rotating brake drive shaft; a conversion member convertinga rotation of the brake drive shaft into a translation movement of thebrake element in the direction towards the brake body, and a rotaryimpact mechanism fitted between the brake drive shaft and theconversion, said rotary impact mechanism including an impact armatureand an elastic member which is directly supported by the impact armatureand configured to apply an elastic force by which the impact armature isurged in a direction of the brake element, wherein the rotary impactmechanism comprises a driving wheel having a first axially projectingdriver, said impact armature having a second axially projecting driverand operatively connected to the brake drive shaft for movement betweenone position in which the impact armature is in engagement with thedriving wheel via the first and second drivers, and another position inwhich the impact armature is disengaged from the driving wheel, saidelastic member biasing the impact armature to seek the first position,said brake drive shaft interacting with the impact armature in such away that a rotation of the brake drive shaft urges the impact armatureto the first position to thereby transfer a torque from the brake driveshaft to the conversion member, and upon further rotation of the brakedrive shaft the impact armature is moved in opposition to an elasticforce by the elastic member to the second position to thereby allow arotation of the impact armature in a first phase and application of arotary impact impulse upon the driving wheel in a second phase as theimpact armature is moved to the first position, and wherein the brakedrive shaft has a helical control groove for engagement of a driving pinof the impact armature.
 10. The brake device of claim 9, wherein therotary impact mechanism is a V-grooved rotary mechanism.
 11. The brakedevice of claim 9, wherein the rotary impact mechanism is a cam rotarymechanism.
 12. The brake device of claim 9, wherein the elastic memberis a helical spring in surrounding relationship to the brake drive shaftto exert the elastic force on the impact armature.
 13. The brake deviceof claim 9, wherein the conversion member has a threaded spindleconnected to the driving wheel.
 14. The brake device of claim 13,wherein the driving wheel is formed in one piece with the threadedspindle.
 15. The brake device of claim 14, further comprising a threadedcup connected to the brake element and guided inside a housing for axialdisplacement, said threaded spindle engaging the threaded cup.
 16. Thebrake device of claim 13, wherein threaded spindle has a self-lockingpitch.